A rifle is a firearm characterized in having a relatively long barrel that allows highly accurate shooting to be carried out from a long distance. Among the different types of known rifles is the bolt-action rifle, which is named so because it includes a part similar to the bolts of old manual locks, i.e. an elongated rod-shaped part, with a bolt handle, which the user manually moves inside another part called the receiver in order to use the rifle. More specifically, the bolt is manually opened after shooting, usually by pulling it backwards, in order to eject the used shell or casing from inside the receiver. Once the receiver has been loaded with a new shell (either manually or automatically), the bolt is pushed forward inside the receiver in order to load the rifle with the new shell and to load the spring unit and firing pin responsible for hitting the back of the shell during firing.
Traditionally, the bolt was composed of a single elongated part provided with a bolt handle in the area of the bolt intended to be located most distant from the rifle barrel. However, new concepts are known where the bolt is divided into several parts, due to different interests. For example, concepts are known in which the bolt handle is removable (see, for instance, U.S. Pat. No. 7,950,177). Other concepts are known in which the elongated body of the bolt is composed of several parts fixed together. For example, bolts comprising a removable bolt head are known (see, for instance, European patent application EP0163129).
Having a bolt with a removable bolt head presents a significant advantage. Legislation in some countries mandates that each rifle is only allowed to have one bolt, and providing a bolt with the possibility of having removable and replaceable bolt heads allows a single bolt to be adapted for different calibre ammunition shells without breaching the aforementioned regulations.
The fact that the bolt head is removable from the bolt is not, however, without risk. In the event that the user of the rifle forgets to fix the bolt head to the bolt body and inserts the bolt body into the receiver without the bolt head, serious accidents could take place during firing. More specifically, the rear area of the shell would not be secured by the bolt because the bolt would be lacking the bolt head on its end and would therefore be shorter than the correct length; then, when firing took place, the pressure created in the chamber would push the bullet forward but, at the same time, as the rear part of the shell would not be secured, the resulting pressure would push this shell backwards. One or more of the following could then happen: the shell could split and small fragments could be expelled through the apertures in the action; the jet of hot air generated by the shot could also be expelled though the apertures; the shall case could push the firing pin backwards and the firing pin could be projected outwardly towards the shooter's face; the entire bolt could come out backwards.
Thus it has been discovered that needs exist for mechanisms to prevent the user of a bolt-action rifle or other firearm equipped with a removable bolt head from being able to assemble the bolt inside the receiver without the bolt head. It is to the provision of a firearm meeting these and other needs that the invention is primarily directed.